I have recently started interning at a stable with a fellow (we'll call him Tom) that is really experienced with horses. He runs a trail riding stables and is a good roper. His horses are very healthy and love their job even though some of them have been doing it for years, almost every day. He mentioned that alfalfa made some of his horses jittery and hard to handle on the trail, and when he switched them back to Timothy they were fine. I asked if maybe that was the reason my mare was so hyper under saddle. (Shannon gets fed about 7 pounds of Alfalfa in the morning.) He said that was probably the problem, given she's normally calm. It makes sense. I only work her 2 or 3 times a week for an hour each time, so I don't want her to have a lot of energy.
But when I talked to my stable owner (let's call him James) he said that was not the problem and that, no, alfalfa doesn't give horses energy or make them 'hot.' He said it would make no difference to switch Shannon's hay. He also said that without alfalfa hay, she couldn't and wouldn't build muscle because of lack of protein...
So I just don't know what to do! I respect both James and Tom and they're both excellent with horses and horse care. I don't want to ignore either ones advice. But my main concern is what's best for my horse, not their ego. Right now, Shannon gets 7 pounds of Alfalfa in the morning and 7 pounds of Timothy at night. She doesn't have any grass to eat and no space to work off her energy - the only time she gets exercise is when I work with her. If I switch her to straight Timothy, will she not be able to gain muscle mass? I'm worried Timothy doesn't have enough nutrients in it. And she doesn't get any kind of supplement. If it makes any difference, she's fat as a barrel. The horses at the trail riding stable live in a similar situation - no grass and not much space to run around in. The only difference is they're worked more.
I've been thinking about switching for awhile just to see if it makes a difference, but I would like more opinions first.